1. Field of the Invention
The present invention relates to a display apparatus and it particularly relates to the display apparatus which includes field-effect type transistors therein.
2. Description of the Related Art
Recently organic electro luminescent (EL) display apparatus employing organic light emitting diodes (hereinafter referred to as OLED) as luminous elements are attracting much attention as display apparatus to replace CRTs and LCDs. For example, display apparatus including field-effect transistors, such as thin film transistors (hereinafter simply referred to as TFT), as elements for driving OLEDs is a subject of intensive research and development activities. In active-matrix type organic EL display apparatus, each pixel is provided with a switching TFT which stores luminance data and thereby enables light emission even at times when luminance data are not written.
With such organic EL display apparatus, a drive margin of luminance data to be supplied to the gate electrode of an OLED driving TFT changes with the current driving capability of each driving TFT as will be described later.
On the other hand, in recent years, the apparatus incorporating semiconductor devices have been growing smaller and lighter, thus requiring the TFTs mounted thereon to be smaller. Moreover, it is expected that the power consumption of such transistors be reduced by the use of smaller TFTs.